1. Field of the Invention
The present invention relates to a disconnection switch which constitutes a make/break apparatus, and more particularly to an solid insulated disconnection switch whose a size is reduced by employing an insulating solid, compared to the size of a conventional disconnection switch.
2. Description of the Background Art
A disconnection switch serves to break off a circuit after stopping a flow of an electric current and is different from a load/break switch in that the disconnection switch does not stop and allow the flow of the current. The disconnection switch is a component of a make/break apparatus which is installed in a power-transmission site or a substation to break off the circuit when a connection to a main circuit need to be changed with the flow of the current being stopped.
The disconnection switch is housed in an airtight metal container whose an inside is filled with an insulating material such as air, or a SF6 gas having more insulative effect than air, in order to keep the main circuits insulated from each other or the earth.
The disconnection switch comes in many switching structures, which performs the connection to and disconnection from the main circuit, with the flow of the electric current being stopped. The disconnection switch within the make/brake apparatus using the SF6 gas, as shown in FIG. 1, is now described.
FIG. 1A is a front view illustrating that the conventional disconnection switch is in a disconnected state. FIG. 1B is a front view illustrating that the conventional disconnection switch is in a disconnected state. FIG. 2 is a plane view of the conventional disconnection switch as shown in FIG. 1A.
The disconnection switch includes a main bus 201 provided in the inside of an container 210 which is filled with an insulating gas, a stator 230 fixed to the main bus 201, a mover 220 which rotates to be connected to or be disconnected from the stator 230 and is coupled to a bushing 202, a driving unit 260 driving the mover 220, a power transfer shaft 240 transferring power generated from the driving unit 260, and a linker 250 which transfers the power to and maintains a disconnection from the main circuit.
FIG. 1A is a front view illustrating that the conventional disconnection switch is in a disconnected state. The disconnected state means that the disconnection switch is disconnected from the main circuit, more specifically that the mover 220 is disconnected from the stator 230.
The driving unit 260 driven by a motor, when receiving an electric connection signal in the disconnected state, rotates the power transfer shaft 240, for example, by 50 degrees counterclockwise. As a result, the linker 250, which is connected to the power transmission shaft 240 using a pin, moves downwards and rotates by 50 degrees counterclockwise to a place where the linker 250 is positioned as shown in FIG. 1B. Accordingly, the mover 220 is coupled to the stator 230, so that the main bus 201, the stator 230, the mover 220, and the bushing 202 are electrically connected to each other, making it possible to operate the make/brake apparatus. This is hereinafter referred to as “the connected state”
Conversely, the driving unit 260, when receiving an electric disconnection signal in the connected state, rotates the power transfer shaft 240, for example, by 50 degrees clockwise. As a result, the linker 250, which is connected to the power transfer shaft 240 using a pin, moves upwards and rotates by 50 degrees clockwise to create the disconnected state that the mover 220 are disconnected from the stator 230.
In the make/brake apparatus having double main buses, the disconnection switch is provided to each of the double main buses. So, when one main bus is in trouble, it is possible to provide electric power using the other main bus. The arrangement of the double main buses in the make/brake apparatus depends on the positional relationship between the main bus and the container 210. The main buses are practically provided in parallel to each other.
The recent trend towards automation, miniaturization, high reliability, and low cost requires the make/brake apparatus including the above disconnection switch to be developed in such a way as to follow the recent trend.
To that end, in addition to performing a basic function of changing the connection to the main circuit with the flow of the electric current being stopped, the disconnection switch has to minimize an insulation space required between the main circuits (corresponding to phases) and between the main circuit and the earth to reduce the size of the make/brake apparatus.
However, the use of the gas places as the insulating material imposes a limitation on reducing the size of the make/brake apparatus including the disconnection switch.
The reduction of the size of the disconnection switch has been achieved by providing insulating solid material barriers between some components of the disconnection switch instead of using the insulating gas, or increasing the gas pressure to maintain the insulation between the components of the disconnection switch. This makes it possible to largely reduce the size of the disconnection switch and requires everyday maintenance operations such as the cleaning of main buses, the checking of the gas pressure, or the like. The use of SF6 gas as the insulating gas in the disconnection switch is regulated worldwide, because SF6 gas is the main culprit increasing the atmosphere temperature.